nbd: Add version 3.20

Add user mode tools for nbd (nbd-server, nbd-client)

Note, that there is also a nbd server provided by qemu (qemu-nbd) which
is able to serve qcow2 formated files.

Usage example:

    if nbd-client -c /dev/nbd0; then
        sudo nbd-client -d /dev/nbd0
    fi
    if test -e server.pid; then
        kill $(cat server.pid)
        rm server.pid
    fi
    test -e /scratch/local2/test.qcow && rm /scratch/local2/test.qcow
    qemu-img create -f qcow2 /scratch/local2/test.qcow 80T
    qemu-nbd --persistent /scratch/local2/test.qcow &
    echo $! > server.pid
    sudo nbd-client localhost /dev/nbd0
    sudo mkfs.ext4 /dev/nbd0
    sudo mount /dev/nbd0 /mnt

Create bee file with

    cp scripts/mTEMPLATE.be0 nbd.be0

and fix BEE_VERSION, info URL and SRCURL.

nbd.be0

@@ -0,0 +1,37 @@
+#!/usr/bin/env beesh
+
+# BEE_VERSION nbd-3.20-0
+
+# more info: https://github.com/NetworkBlockDevice/nbd
+
+SRCURL[0]="https://downloads.sourceforge.net/project/nbd/nbd/$PKGVERSION/nbd-$PKGVERSION.tar.xz"
+
+# PATCHURL+=()
+
+# build_in_sourcedir
+
+# sourcesubdir_append src
+
+#mee_extract() {
+#    bee_extract "${@}"
+#}
+
+#mee_patch() {
+#    bee_patch "${@}"
+#}
+
+#mee_configure() {
+#    bee_configure
+#}
+
+#mee_build() {
+#    bee_build
+#}
+
+#mee_install() {
+#    bee_install
+#}
+
+#mee_install_post() {
+#    exit
+#}